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RESEA R C H Open Access
First-line chemoimmunotherapy in metastatic
breast carcinoma: combination of paclitaxel and
IMP321 (LAG-3Ig) enhances immune responses
and antitumor activity
Chrystelle Brignone
1
, Maya Gutierrez
2
, Fawzia Mefti
2
, Etienne Brain
2
, Rosana Jarcau
2
, Frédérique Cvitkovic
2
,
Nabil Bousetta
2
, Jacques Medioni
3
, Joseph Gligorov
4
, Caroline Grygar
1
, Manon Marcu
1
, Frédéric Triebel
1*
Abstract

Background: IMP321 is a recombinant soluble LAG-3Ig fusion protein that binds to MHC class II with high avidity
and mediates APC and then antigen-experienced memory CD8
+
T cell activation. We report clinical and biological
results of a phase I/II in patients with metastatic breast carcinoma (MBC) receiving first-line paclitaxel weekly, 3
weeks out of 4.
Methods: MBC patients were administered one dose of IMP321 s.c. every two weeks for a total of 24 weeks (12
injections). The repeated single doses were administered the day after chemotherapy at D2 and D16 of the 28-day
cycles of paclitaxel (80 mg/m
2
at D1, D8 and D15, for 6 cycles). Blood samples were taken 13 days after the sixth
and the twelfth IMP321 injections to determine sustained APC, NK and memory CD8 T cell responses.
Results: Thirty MBC patients received IMP321 in three cohorts (doses: 0.25, 1.25 and 6.25 mg). IMP321 induced
both a sustained increase in the number and activation of APC (monocytes and dendritic cells) and an increase in
the percentage of NK and long-lived cytotoxic effector-memory CD8 T cells. Clinical benefit was observed for 90%
of patients with only 3 progressors at 6 months. Also, the objective tumor response rate of 50% compared
favorably to the 25% rate reported in the historical control group.
Conclusions: The absence of toxicity and the demonstration of activity strongly support the future development
of this agent for clinical use in combined first-line regimens.
Trial registration: ClinicalTrials.gov NCT00349934
Background
Traditionally, the goal of chemotherapy has been seen as
direct cytotoxicity and induction of tumor cell death.
However, the immunoadjuvant effect of chemotherapy,
where the immune response induced by tumor cell
death mediates the suppression of tumor growth and
determines the long-term survival of patients, is now
well established. For instance, in breast cancer patients
who receive adjuvant chemotherapy, the analysis of
metastasis-free survival showed an overall significantly

lower percentage of metastasis-free patients in the
group with mutated TLR4 [1]. The effect of the TLR4
mutation is to reduce antigen-presenting cell function.
Such patients could not benefit fully from the immuno-
logical component of chemotherapy, i.e. the induction of
cytotoxic CD8 T cell responses to tumor antigens
released by dying tumor cells. A simila r observ ation has
been reported more recently in advanced colon cancer
treated with oxaliplatin [2] and further supports the idea
that apoptotic cell death induced by chemotherapy leads
to a beneficial immunoadjuvant effect [1,3,4]. Enhancing
such chemotherapy-induced T cell responses by giving a
non-specific immunostimulatory factor which induces
the antigen presenting cells (APCs) to mature and trans-
port the tumor antigens to the lymph nodes for presen-
tation to T cells would make such a combination
* Correspondence:
1
Immutep S.A., (2 rue Jean Rostand), Orsay, (91893), France
Brignone et al. Journal of Translational Medicine 2010, 8:71
/>© 2010 Brignone et al; licensee BioMed Central Ltd. This is an Open Access article distributed unde r the terms of the Creative
Commons Attribution License ( which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cit ed.
therapy very attractive. This therapeutic approach is
supported by preclinical studies which have shown
synergy between chemotherapy and immunotherapy i n
carcinomas [5-8].
The soluble LAG-3Ig fusion protein (or IMP321) is a
first-in-class immunopotentiator targetin g MHC class II
+

APCs [9-12]. It has bee n tested in previously-treated
advanced renal cell carcinoma patients known to be
immunosuppressed and shown to induce an increase in
the percentage of circulating activated CD8 T cells and
of long-lived effector-memory CD8 T cells in all patients
treated by repeated injections over 3 months, without
any detectable toxicity [13]. Importantly, a concentration
of only a few ng/mL IMP321 has been shown to be
active in vitro on APC, showing the great potency of
IMP321 as an agonist of the immune system [13].
In this report, data are presented demonstrating that
IMP321 expanded and activated for several months both
the primary target cells (MHC class II
+
monocytes/den-
dritic cells) to which IMP321 binds, and the secondary
target cells (NK/CD8
+
effector memory T cells) which
are activated subsequently. By pooling results from all
30 patients and comparing tumor regression with an
appropriate historical control group, we saw a doubling
of the objective response rate which suggests that
IMP321 is a potent agonist of effective anti-cancer cellu-
lar immune responses in this clinical setting.
Methods
Patients
Patient characteristics are shown in Table 1. Eligible
patients were at least 18 years old, had histologically
documented stage IV breast adenocarcinoma, an Eastern

Cooperative Oncology Group performance status of 0 or
1, measurable disease, adequate bone marrow, liver and
renal function, and life expectancy of at least 3 months.
Previous hormonal therapy for metastatic breast cancer
or cytotoxic adjuvant chemotherapy was allowed. Bipho-
sphonat e therapy was allowed if started at least 4 w eeks
prior to first dosing of the study drug.
Patients were excluded if they were candidates for
treatment with trastuzumab, had received prior che-
motherapy for metastatic breast adenocarcinoma, or
radiotherapy within the 30 days prior to fir st dosing of
the study drug, known cerebral metastases or had a dis-
ease-free interval of less than 12 months from last dose
of adjuvant chemotherapy.
Pregnant or nursing women were excluded. Women
of childbearing potential were required to h ave a nega-
tive pregnanc y test within 7 days of treatment initiation
and to use adequate birth control measures during the
study. Patients were excluded if they had severe allergy,
known clinically active autoimmune disease requiring
immunosuppressive therapy, known active hepatitis B or
C, known HIV positivity, or had any condition that was
unstable or could jeopardize their safety or ability to
comply with study procedures, o r could interfere with
evaluation of the results. All patients gave written,
informed consent to p articipate in the study, which was
conducted in accordance with the Declaration of Hel-
sinki, the Good Clinical Practice guidelines, and all
applicable local laws and regulations. The study protocol
and amendments were approved by an institutional

review board and an independent ethics committee.
Study design and treatments
In this multi-center open-label, non-randomized, fixed
dose-escalation phase I/II trial performed in an ambula-
tory and day-hospital setting, patients were administered
one dose of IMP321 s.c. every two weeks for a total of
24 weeks (12 injections in total). The repeated single
doses were administered on D2 and D16 of each 28-day
cycle of paclitaxel (80 mg/m
2
of paclitaxel via 1-hour
infusion at D1, D8 and D15 of every 28-day cycle for 6
cycles), i.e. on the day after chemotherapy (Fig.1).
Twenty mg i.v. dexamethazone were given in the first
cycle before each paclitaxel infusion. Corticosteroids
Table 1 Patients characteristics
Number of patients n = 30
Years of age – median (range) 64 (47-78)
Estrogen-receptor status – no. (%)
Positive 26 (87%)
Negative 4 (13%)
Progesterone-receptor status – no. (%)
Positive 18 (60%)
Negative 12 (40%)
HER2 status – no. (%)
Positive 0 (0%)
Negative 30 (100%)
Previous adjuvant chemotherapy – no. (%)
None 3 (10%)
Anthracycline 15 (50%)

Anthracycline + Taxane 8 (27%)
Vinorelbine 1 (3%)
Disease-free interval – no. (%)
≤ 24 mo 7 (23%)
> 24 mo 23 (77%)
Extent of disease – no. (%)
≥ 3 sites 22 (73%)
< 3 sites 8 (27%)
Location of disease – no. (%)
Visceral 21 (70.%)
Non Visceral 9 (30.%)
ECOG Status
0 7 (23%)
1 22 (73%)
Brignone et al. Journal of Translational Medicine 2010, 8:71
/>Page 2 of 11
were not administered after the first chemotherapy cycle
if the first 3 i.v. infusions of paclitaxel wer e well
tolerated.
Eight to fourtee n patients were enrolled in successive
cohorts with the following IMP321 dosing: 0.25 mg,
1.25 mg and 6.25 mg per injection (Fig.1). To be evalu-
able for the decisio n to proceed with the next cohort at
a higher dose level, a patient must have received at least
12 weeks of treatment with IMP321. Toxicities were
assessed using the National Cancer Institute Common
Toxicity Criteria version 3.0. Dose-limiting toxicity
(DLT) was defined as any grade 3-4 toxicity. If one
patient had developed a DLT, dose escalation would
have been stopped and the prior dose level considered

the maximum tolerated dose (MTD). No intra-patient
dose escalation was permitted. Also, because of the
fixed-dose study design no dos e reduction f or a patient
was allowed.
Study assessments
Before initiating treatment, each patient was evaluated
for medical history, physical ex amination , tumor m ea-
surement using computer-assisted tomography, Eastern
Cooperative Oncology Group performance status, com-
plete differential blood count, serum chemistry, urinaly-
sis, and elect rocardiogram . These assessment s were also
done before each subsequent injection. All observations
were recorded, including results of ph ysical examina-
tions, vital signs, adverse events, concomitant medica-
tions, and laboratory tests. Patients were monitored
every 2 weeks and as nee ded for adverse events. Tumor
respon se and progression were asse ssed using Response
Evaluation Criteria in Solid Tumors (RECIST) version
1.1 [14] with imaging studies done 2 w eeks after the
sixth and the twelfth injections. Sera were collected at
baseline (D1) and two weeks after the twelfth (day 170)
injection for detection of serum anti-IMP321 antibodies.
Blood samples were collected in lithium heparin-
containing tubes at the same time points and also two
weeks after the sixth injection (day 85) for monitoring
both the APC (monocytes, dendritic cells) and CD8
T cell immune responses.
Detection of anti-IMP321 antibodies
Serum samples obtained at baseline and day 170 after
the initial dosing were tested for antidrug antibodies

using ELISA. The serum was diluted 1:100 to avoid
matrix effect, l oaded (at least two determinations/sam-
ple) on microtiter plates (Ma xisorb, NUNC) precoated
with IMP321 (1 μg/well) and revealed by a mix of HRP-
conjugated goat anti-human kappa and goat anti-human
lambda antibodies (Serotec). As controls, various
concentrations of a recombinant human monoclonal
antibody fragment Fab- dHLX-MH directed to IMP321
produced from human Ig library in E . coli (MorphoSys,
Martinsried, Germany) were added to each plate and
the assay sensitivity was 3 ng/ml Fab equivalent. Optical
densities (OD) were determined at the wavelengths of
450 and 600 nm.
The sera from some patients were also assessed in a
bridging immunogenicity assay using the electrochemilu-
minescence Meso Scale Discovery (MSD) analyzer [ 15].
Briefly, any drug-specific antibodies present in undiluted
serum samples were captured and revea led by biotin-
and SULFO-Tag-conjugated IMP321 respectively, on
streptavidin-coated plates. An anti-LAG-3 mAb (17B4)
diluted in neat human AB (Jacques Boy) was used a s
reference standard (see [13] for details).
Pharmacodynamics
Blood samples were collected pre-dosing at D1, D85 and
D170 and directly stained with BD Multitest CD8-FITC/
Figure 1 First-line chemo-immunotherapy: drug administration schedule. The repeated single doses of IMP321 (0.25, 1.25 and 6.25 mg s.c.
12 × q14) were administered on D2 and D16 of the 28-day paclitaxel cycle, i.e. on the day after chemotherapy. A fixed dose of paclitaxel (80
mg/m
2
) was given as a weekly, 3 weeks out of 4, chemotherapy regimen for 6 cycles.

Brignone et al. Journal of Translational Medicine 2010, 8:71
/>Page 3 of 11
CD38-PE/CD3-PerCP/HLA-DR-APC, with BD Multitest
6-color TBNK (CD3-FITC/CD16-PE+CD56-PE/CD45-
PerCPCy5.5/CD4PE-Cy7/CD19-APC/CD8-APC-Cy7),
BD Simultest LeucoGate (CD45-FITC/CD14-PE) in
tubes containing a precise number of fluorescent control
beads (BD Trucount
™ tubes, BD Biosciences). After lysis
of red blood cells using the BD FACS l ysing solution,
cells were analyzed using a 6-color FACSCanto cyt-
ometer and the absolute number of cells per μl of whole
blood was calculated using the numbe r of control beads
acquired in each sample. For patients in the 1.25 and
6.25 mg groups, cells were also directly stained in
BD Trucount
™ with CD45-APC-Cy7, CD14-PerCP, anti-
HLA-DR-PE-Cy7 and different combinations of mono-
cyte activation markers: CD11a-FITC, CD11b-PE,
CD16-PE, CD35-FITC, CD54-PE, CD64-FITC, CD80-PE
and CD86-FITC. The expression of these markers on
monocytes was directly proportional to the cell-bound
fluorescence. The results are shown after normalization
of the cell-bound fluorescence against the fluorescence
of control beads.
PBMCs were isolated by centrifugation over Ficoll-
Paque (GE Healthcare) using LeucoSep® tubes (Greiner
Bio-One). Fresh PBMCs were stained with CD45-FITC,
CD14-PerCP, CD16-PE-Cy7, HLA-DR-APC-Cy7,
CD11c-APC and CD123-PE antibodies to determine the

percentage of plasmacytoid (pDC, CD45
+
CD14
-
CD16
-
HLA-DR
+
CD123
+
CD11c
-
) and myeloid (mDC, CD45
+
CD14
-
CD16
-
HLA-DR
+
CD123
-
CD11c
+
) dendritic cells
in CD45
+
cells. Cells (0.3-1.0 × 10
6
)werewashedin

Dulbecco’s phosphate-buffered saline (Invitrogen) 0.5%
bovine serum albumin (PAA Laboratories), 0.1% sodium
azide (Sigma-Aldrich), and incubated with t he mixture
of fluorochrome-conjuga ted antibodies (all from BD
Biosciences) for 30 min at 4°C. After wash ing, cells were
analyzed by cytometry. The remaining cells were frozen
in fetal calf serum (Hyclone) supplemented with 10%
DMSO (Sigma-Aldrich). Following completion of the
protocol, series of PBMC samples for each individual
were thawed and stained with CD3-PerCP-Cy5.5, CD8-
APC-Cy7, CD45RA-PE-Cy7, CD45RO-APC and CD62L-
FITC antibodies to determine the percentage of CD8
+
T
cells (secondary target cells) with a terminally differen-
tiated CD45RA
+
effector memory (EM) phenotype.
These EMRA cells are CD3
+
CD8
+
CD45RA
+
CD45RO
-
CD62L
-
.
Statistical analysis

The paired non-parametric Wilcoxon signed rank test
was used to compare the immunomonitoring and clini-
cal values obtained at the different time points. Only
patients with all available time points were included in
the immunomonitoring analysis. Spearman rank correla-
tion coefficients w ere estimated for bivariate analyses.
The apriorilevel of significance was a p-value of
< 0.05. Data was computed using JMP® software.
Results
Safety
Two out of the 33 enrolled patients were removed from
the 1.25 mg arm of the study early on and were replaced
because of persistent grade 3 paclitaxel-related neuropa-
thy. A third case received one injection IMP321
(6.25 mg) and was removed from the study due to
ineligibility. All the other 30 patients received at least
6 doses of IMP321 and were included in both the safety
and efficacy analyses. No clinically significant local or
systemic IMP321-related a dverse events were recorded,
in line with a previous study in which IMP321 was used
alone (i.e. without chemotherapy) [13]. With the combi-
nation therapy, six grade 3 adverse events were recorded
(four in the 0.25 mg group and one in the 1.25 mg and
6.25 mg group e ach): asthenia (3 cases), neuropathy,
allergic reaction and neutropenia. In addition, one
patient in the 0.25 mg group had appendicitis, one
patient i n the 1.25 mg group a Staphylococcus infection
and one patient in the 6.25 mg group an accidental hip
bone fracture.
Detection of anti-IMP321 antibodies

Sera collected at baseline and two weeks after the
twelfth injection (day 170) were assayed for anti-IMP321
antibodies by direct ELISA (Additional file 1). Two
patients receiving 1.25 mg (patients #11 and #12)
showed an increase compared to baseline level by more
than 15%. The sera from these (and other) patients were
then assayed without any dilution in a very sensitive
bridging immunogenicity assay using the MSD analyzer
[15]. The tested sera gave a signal below the detection
range (2 ng/ml). Repeated injection of IMP321 up to
6.25 mg did not induce anti-IMP321 antibodies.
Pharmacodynamics
Blood samples were tested 13 days after each IMP321
injection (i.e. just before the chemotherapy and 24 hr
before the next IMP321 injection): therefore only
sustained cell activation or cell subset expansion was ana-
lyzed. Immunomonitoring in fresh whole blood showed
significant increases of monocytes (CD45
+
CD14
+
,
20 patients out o f 24), NK cells, (CD3
-
CD16
+
CD56
+
,
15 out of 24) and activated (CD38

+
HLA-DR
+
)CD8T
cells (17 out of 24) in absolute numbers per μloffresh
whole blood on D170 compared to D1 (Fig. 2 panel A).
Increases in the expression on blood monocytes of
adhesion molecules (CD11a, CD11b, CD54), receptors
for immunoglobulins (CD16 and CD64), complement
(CD35) and co-stimulation molecules (CD80 and CD86)
were consistently observed in patients receiving the 6.25
Brignone et al. Journal of Translational Medicine 2010, 8:71
/>Page 4 of 11
mg but not the 1.25 mg dose (Fig. 3A). To assess the
functionality of monocytes after treatment, w e consid-
ered the upregulation of the expression of any one of
these 8 independent markers by more than 50% to be a
gain of function. In the 1.25 mg-group, 28% of patients
expressed a gain of function at D170 compared to D1
while 83% of patients in the 6.25 mg group did so (Fig.
3B). In additio n, the gain of function was much more
pronounced in the latter grou p as more than 50% of
these patients upregulated at least one marker at D85
and 3 markers at D170 (Fig. 3B). The scores were calcu-
lated by multiplying the percentage of patients by the
number of markers to apply more weight to patients
presenting an increase in several activation markers.
When the weighted scores of the two groups are com-
pared using the non-parametric Wilcoxon test, we
observed a greater activation index for the 6.25 mg-

group than for the lower dose groups with borderline
statistical significance (p = 0.06 at D170).
Immunomonitoring of PBMCs showed an increase in
the percentages of plasmacytoid and monocytoid dendritic
cells (pDC, 24 patients out of 25, mDC, 21 out of 25) and
CD62L
-
CD45RA
+
effector-memory (EMRA, 21 patients
out of 26) CD8 T cells which represent the most differen-
tiated type of CD8
+
T cells (Fig. 2 panel B) [16,17].
In conclusion, we have seen an effect on:
- primary target cells (i.e. MHC class II
+
cells): the
treatment increased the absolute numbers in whole
blood as well as the percentages in PBMCs of APC
(monocytes and dendritic cells). Monocytes were more
activated at the higher IMP321 dose level for at least
3 months (i.e. from D85 to D170).
- secondary target cells: the treatment increased the
absolute numbers of NK and activ ated CD8 T cells per
μl of fresh whole blood as well as the percentage of
CD8
+
T cells with a terminally differentiated effector
memory phenotype in PBMCs. These CD8 T and NK

subsets are known to display a high anti-tumor activity.
Efficacy
According to the protocol, 30 patients were retained for
analysis out of the 33 enrolled patients. The three drop-
Figure 2 IMP321 increases the numbers of monocytes, NK and activated CD8 T cells in blood (panel A). Fresh blood samples were
collected pre-dosing, at D1, D85 and D170 and directly stained with fluorochrome-conjugated antibodies in tubes containing a precise number
of fluorescent control beads. The results show the mean ± sd of the absolute numbers of CD45
+
CD14
+
(monocytes), CD3
-
CD56
+
(NK cells) and
CD38
+
HLA-DR
+
CD8
+
(activated CD8
+
cells) cells. The paired non-parametric Wilcoxon signed rank test was used to compare increases observed
between D85 or D170 and D1. When significant (< 0.05), p values are indicated. IMP321 increases the percentages of dendritic cells and
cytotoxic CD45RA
+
Effector-Memory CD8
+
T cells (EMRA) in PBMCs (panel B). PBMCs cells collected pre-dosing, at D1, D85 and D170 were

isolated and stained with fluorochrome-conjugated antibodies and analyzed by flow cytometry. The results show the mean ± sd of the
percentages of plasmacytoid dendritic cells (pDC, CD45
+
CD14
-
CD16
-
HLA-DR
+
CD123
+
CD11c
-
) and myeloid dendritic cells (mDC, CD45
+
CD14
-
CD16
-
HLA-DR
+
CD123
-
CD11c
+
) in CD45
+
cells, as well as the percentages of CD45RA
+
CD45RO

-
CD62L
-
in the CD8
+
T cell population (CD45RA
+
EM
CD8 T cells or EMRA). The significant Wilcoxon p values are indicated.
Brignone et al. Journal of Translational Medicine 2010, 8:71
/>Page 5 of 11
Figure 3 IMP321 increases the expression of activation markers on blood monocytes. Blood samples were collected pre-dosing, at D1,
D85 and D170 and directly stained with fluorochrome-conjugated CD45, CD14, anti-HLA-DR and CD11a, CD11b, CD16, CD35, CD54, CD64, CD80
or CD86 antibodies in tubes containing a precise number of fluorescent control beads. The expression of activation markers on monocytes was
directly proportional to the cell-bound fluorescence. The results shown in panel A are the mean ± sd after normalization of the cell-bound
fluorescence against the fluorescence of control beads. Statistically significant increases between D85 or D170 and D1 are analyzed using
Wilcoxon signed rank test and significant p values (< 0.05) are shown. In panel B, the percentage of patients showing increases in the expression
of the indicated numbers of activation markers at D85 or D170 compared to the baseline at D1 was calculated. The number of markers (n)
displaying an increase by at least 50% was calculated for each patient in the 1.25 mg (7 patients) and 6.25 mg (12 patients) groups. The pie
charts represent the percentages of patients with increases in the indicated number of markers.
Brignone et al. Journal of Translational Medicine 2010, 8:71
/>Page 6 of 11
out patients received just one or a few IMP321 injec-
tions (see Safety). The percentage change in the sum of
tumor diameters at the end of treatment are shown in
Fig. 4 as a waterfall plot. Only 3 out of 30 patients had
progressive disease (10%) and 15 benefited from an
objective tumor response (50%).
The historical control group is derived from the ECOG
2100 study, the only randomized phase III study with a

very similar chemotherapy administration schedule using
90 mg/m
2
paclitaxel given on days 1, 8 and 15 every 4
weeks until disease progression [18]. In the subgroup of
patients with measurable disease at inclusion (like our
patients) the response rate was 25% (64 patients with par-
tial or complete response out of 254). Progression-free sur-
vival (PFS) in the hist orical control group was o nly 5.6
months and therefore more than 50% of the patients were
classified at 6 months as having p rogressive disease (PD,
Fig.4).Inourcase,only3patientsoutof30(i.e.10%)were
PD. Similarly, the objective response rate in the historical
control group of 25% can be compared to our response
rate of 15 patients out of 30 t reated (50%) ( Fig. 4).
Closer analysis of the respon se at the different time-
points reveals a particularly interesting difference in the
time-profile of the response compared to paclitaxel
alone. With chemotherapy alone, most of the tumor
regression is usually observed during the first 3 months.
This induction phase corresponds here to the period
from D1 to D85. The changes in mean sum of tumor
diameters and in mean percentage of t umor diameter
regression for patients with available D85 and D170 tar-
get lesion measurements a re shown in Fig. 5 panel A
and panel B, respectively. In contrast to chemotherapy
alone, further significant tumor regression was observed
during the maintenance phase of the treatment (i.e.
D85-D170), especially at the highest IMP321 dose
(6.25 mg) where statistical significance was reached.

The mean tumor diameter regression perc entage cal-
culated on the 15 PR (Fig.5, panel C) was 40% in the
first 3 mo nths (i.e. induction chemotherapy between D1
and D85) in patients with an objective clinical response
and a further 29% (i.e. D170 versus D85) in the next
3 months (i.e. maintenance chemotherapy between D85
and D170). In volumetric terms this corresponds to a
shrinkage of 74% in the first three months (i.e. D85 ver-
sus D1) follow ed by a further 50% in the second three
months (i.e. D170 versus D85).
Moreover, none of the patients receiving the lowest
dose (0.25 mg) of IMP321, and experiencing an objective
response after 6 months of treatment, had an objective
tumor regression between D85 and D170. In contrast,
50% and 71% of patients in the 1.25 mg and the 6.25 mg
groups, respectively, had a further objective clinical
response during the last 3 months (data not shown).
The change in tumor size (mean sum of tumor
diameters at post-study relative to pre-study) is signifi-
cantly correlated (Spearman rank correlation coefficient
r = -0.4) with the absolute number of monocytes
(CD45
+
CD14
+
) per μl of blood at D1 (Fig. 6A). Note that
the normal range for m onocytes is 0.3 - 0.8 × 10
9
CD45
+

CD14
+
cells/l whole blood [19] and therefore many
patients and especially the poor responders are monocyto-
penic at D1.
Figure 4 Clinical results: comparison with historical control group. The water fall plot presents the per centage of change in the sum of
tumor diameters observed after treatment (6 months) for individual patients. The patients experiencing progressive disease (PD), stable disease
(SD), or partial response (PR) are shown in white, grey and black, respectively. Patients 1-8 received 0.25 mg, patients 9-18 1.25 mg and patients
19-33 6.25 mg IMP321. Asterisks show the 4 patients with 3 months treatment instead of 6 months. Historical data obtained for a group
receiving paclitaxel alone are presented as dotted lines.
Brignone et al. Journal of Translational Medicine 2010, 8:71
/>Page 7 of 11
We also analyzed whether there was a difference
between responders and non-responders in the 1.25 and
6.25 mg groups in terms of monocyte gain of function,
as defined in Fig.3B. The change in tumor size is signifi-
cantly correlated (Spearman rank correlation coefficient
r = -0.44) with the monocyte gain of function at D170
(Fig. 6B). There was no other significant correlation
with regards to NK or CD8 subsets.
Discussion
First-line chemo-immunotherapy is a new approach to
the treatment of advanced cancer. Chemotherapy drugs
alone induce tumor cell apoptosis and cause modulation
of the immunological environment combined with a
burst of tumor antigen release. The resulting T cell
immune response contributes to the regression of the
tumor [20]. However, this initial immune response
needs to be prolonged and amplified by a T-cell booster
that is non-toxic and can be given repeatedly, such as

IMP321. IMP321 has a direct effect on APC which
express MHC class II giving rise to rapid APC activation
and leading to reactivation and expansion of antigen-
experienced memory CD8 T cells [11].
In the present study, the change in t umor size is cor-
related with the absolute number of monocytes per μlof
blood at D1 (Fig. 6). Notably, poor responders tend to
be monocytopenic. Monocytes are the most common
MHC class II
+
primary target cells for IMP321 in the
blood [12] and therefore it makes sense th at a higher
number of monocytes before treatment should favor the
tumor response to IMP321
We used the w eekly, 3 weeks out of 4, chemotherapy
regimen which was introduced to reduce cumulative
neurotoxicity observed with weekly paclitaxel adminis-
tration [18]. Repeated single doses of IMP321 were
administered on D2 and D16 of the 28-day paclitaxel
cycle, on the day after the chemotherapy, to activate the
antigen-loaded APC. This repeated dose injection proto-
col has been shown separately to be well tolerated for
doses up to 30 mg in advanced cancer patients and to
induce CD8 memory T cell expansion [13].
In the present study, clinical benefit at 6 months was
observed for 90% of patients in contrast to less than
50% of patients (PFS = 5.6 months) in the historical
control group [18]. Also the objective response rate of
50% at the post study visit compared favorably to the
25% response rate in the historical control group [18].

Although the inclusion and exclusion criteria were simi-
lar, the resulting patient populations were not identical
in the two studies. For instance we enrolled older
patients (64 years old compared to 55) and more
patients with extent of disease ≥ 3 sites (73% compared
to 46%, p = 0.007). Future randomized clinical studies
with an internal paclitaxel alone control group will
determine whether the differences observed in the pre-
sent study in terms of clinical benefit hold true.
The clinical benefit of immunotherapy may only
appear after a few months of treatment as it takes time
for active immunotherapy to progressively reinforce the
immune response. For example, in patients treated with
Figure 5 Tumor regression during maintenance chemotherapy.
Mean sums of tumor diameters (panel A) and percentages of tumor
regression (panel B) measured at inclusion (D1) and after 3 months
(D85, i.e. during induction chemotherapy) and 6 months (D170, i.e.
during maintenance chemotherapy) are shown for each dose-
group. The four patients with unavailable D170 data were excluded
from the analysis. Statistically significant decreases between D85 or
D170 and D1 and between D170 and D85 are indicated (see
brackets, * p < 0.05). The mean sums of tumor diameters ± sd
obtained in the 15 patients who achieved an objective response are
shown in panel C (one D170 sum of diameters is missing).
Brignone et al. Journal of Translational Medicine 2010, 8:71
/>Page 8 of 11
ipilimumab, an anti-CTLA-4 neutralizing antibody, t he
patterns of c linical response differ from those seen fol-
lowing cytotoxic chemotherapy. Late responses are fre-
quent and may even occur after an initial period of

tumor progression [21]. In the present study, for the 15
PR, the tumo r regression during maintenance che-
motherapy between D8 5 and D17 0 was n ot much les s than
that seen during induction chemotherapy between D1 and
D85. This level o f maintained response may be a character-
istic and a benefit of chemo-immu notherapy protocols.
To investigate the role of the immune response behind
the above clinica l results, we analyzed both the absolute
numbers of PBMC subsets and any changes in the pro-
portions of key constituents. On top of a significant
increase in the absolute number of monocytes, NK cells
and activated CD8 T cells, we observed an increase in the
proportion of the EMRA CD8
+
T cell subset. The impor-
tance of this subset in cancer was highlighted when it
was shown for the first time that circulating EMRA cells
exert ex vivo tumor-specific cytolytic activity in mela-
noma patients [22]. These EMRA cells have been charac-
terized as terminally differentiated CD8 T cells
potentially able to home into inflamed tissues such as the
tumor microenvironment because they have lost the
CD62L and CCR7 lymphoid homing receptors [16,17].
Memory T cells are generated and stored in secondary
lymphoid organs, such as lymph nodes, spleen and the
bone marrow [23]. There is a h igh frequency of memory
Tcellsagainstbreasttumor-associatedantigenMHC
class I-restricted peptides in the bone marrow of breast
cancer patients [24]. Given that it is only after several
rounds of proliferation that memory T cells appear in

the peripheral blood, it may well be that the significant
and sustained increase in EMRA CD8 T cells in the
blood of our patients is an indication of a much greater
expansion in the secondary lymphoid organs.
Importantly, EMRA cells are one of the long-lived T
cell subsets. We have shown that a long-lived EM subset
was increased by IMP321 in renal cel l carci noma
patients [13]. Successful active immunotherapy may
depend not upon a transient increase in short-lived
effector T cells but rather upon the progressive reinfor-
cement of these vital long-l ived effector-memory sub-
sets. If this is true it could explain why successful active
immunotherapies exert their effects over years [25].
Although the anti-cancer mechanism of action of pacli-
taxel is initially due to effects on b-tubulin, growing evi-
dence supports anti-tumor effects through innate immune
activation and possibly through TLR4/MD-2 activation. In
the mouse, paclitaxel can mimic bacterial LPS by activat-
ing macrophages and DC [26]. H owever this action of
paclitaxel on mouse MD-2/TLR4 is in contrast with the
observation that paclitaxel associates with human MD-2
in vitro without promoting TLR4 activation [27].
In patients, there is also circumstantial evidence that
paclitaxel can stimulate the immune response against
cancer. A clinical study indicated that the development
of a lymphocytic infiltrate after chemotherapy correlated
with a positive response to neoadjuvant paclitaxel therapy
[3]. Like ma ny cytotoxic compounds, paclitaxel may have
an immuno-adjuvant effect that relies on the capacity of
Figure 6 Correlation between the number of monocytes

before treatment and tumor regres sion (Panel A).The
absolute numbers of monocytes per μlofbloodatD1areplotted
as a f unction of the percentages of change in the mean sum of
tumor diameters at D170 versus D1 (correlation coefficient r =
-0.4; p < 0.05). Correlation between the monocy te gain of
function at D170 and tumor regression (Panel B). The monocyte
gain of function calculated as the mean of the percentage
increases of each of the eight activation markers in Figure 3A is
plotted as a function of the p ercentages of change in the mean
sum of tumor diameters at D170 versus D1 (correlation coefficient
r =-0.44;p=0.05).
Brignone et al. Journal of Translational Medicine 2010, 8:71
/>Page 9 of 11
APC to engulf dying tumor cells and then process and
present tumor antigens to memory T cells [20]. However,
analyses of PBMC subsets in patients receiving taxane
therapy have not revealed any alterations in these subsets
in terms of percentages or phenotypes [28,29].
The6.25mgIMP321dosewasfoundinthepresent
study to activate monocytes when given repeatedly over
6 months (see Fig.3). The gain of function in this major
APC subset analyzed in fresh whole blood (fresh
because monocytes are known to be very sensitive to
freezing/thawing) was already observ ed at D85 and then
strongly reinforced at D170. This gradual but sustained
activation was o bserved in a circulating APC populat ion
expanded both in terms of absolute numbers per μlof
blood and in terms of percentages of PBMCs. Among
the different activation antigens analyzed, CD54 expres-
sion was incr eased. CD54 upregulation is currently used

as a surrogate for assessing human APC activation and
also as a potency measure of sipuleucel-T, an approved
active cellular immunotherapy product designed to sti-
mulate an immune response against prostate cancer
[25,30]. T hese observations, combined with the lack of
anyIMP321sideeffects,clearlyindicatethata6mg
IMP321 s.c. dose given biweekly for a long period of
time will be a potent administration scheme for pivotal
chemo-immunotherapy trials. We have shown separately
that increasing the dose from 6 to 30 mg do es not seem
to increase the immune response in cancer patients [13].
Conclusions
The next step will be to test immunotherapy combined
with chemotherapy in a first-line setting with patients
with a good immune status, as here, but in randomized
phase II and III clinical trials with standard chemother-
apy as a control arm. If successful this will confirm the
idea that chemotherap y and immunotherapy can form a
practical partnership in the treatment of cancer.
Additional material
Additional file 1: Anti-IMP321 antibodies. Sera collected at baseline
and 2 weeks after the sixth and the twelve IMP321 injections were
tested for the presence of anti-IMP321 antibodies by direct ELISA.
Absorbance values corresponding to various concentrations of an anti-
IMP321 recombinant human Fab antibody fragment (left panel) are
indicated.
Acknowledgements
This work has been supported by funds from Immutep S.A.
Author details
1

Immutep S.A., (2 rue Jean Rostand), Orsay, (91893), France.
2
Centre René
Huguenin, Saint Cloud, France.
3
Hôpital Européen Georges Pompidou, (20
rue Leblanc), Paris, (75908), France.
4
Hôpital Tenon, (4 rue de la Chine), Paris,
(75970), France.
Authors’ contributions
MG, FM, EB, RJ, FC, JM and JG carried out the clinical study. NB helped
collect the data. CB, CG and MM carried out the immunoassays. CB
participated in the design of the study and performed the statistical analysis.
MG and FT conceived the study, and participated in its design and
coordination and helped draft the manuscript. All authors read and
approved the final manuscript.
Competing interests
CB, CG, MM and FT received salaries from Immutep S.A. which holds patents
relating to the content of the manuscript.
Received: 22 March 2010 Accepted: 23 July 2010
Published: 23 July 2010
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doi:10.1186/1479-5876-8-71
Cite this article as: Brignone et al.: First-line chemoimmunotherapy in
metastatic breast carcinoma: combination of paclitaxel and IMP321
(LAG-3Ig) enhances immune responses and antitumor activity. Journal of
Translational Medicine 2010 8:71.
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